They, like all Turing-equivalent languages, are functionally equivalent. You can do everything Ruby can do in PHP, and you can do everything PHP can do in Ruby. Neither is better than the other, they're just different. If you want to try something different, then maybe you'll want to learn Ruby.

Erlang and Clojure are the hacker languages of the month, though. The Ruby fad has passed.

Ruby is apparently higher paying from what I've seen (on average). I'm also in the same boat as you goodmast3r. I've been using PHP for a few years now, and I've just started learning Ruby as of a few days ago. After playing around with true object-orientated and functional languages such as Scala, Fantom and eventually Ruby, I don't think there's anyway I can stick with PHP. I don't have any particular problems with PHP (especially since PHP5.3), other than languages such as Ruby are simply nicer.